CHEMISTRY, 
248 
varais, where it Is of different colours, gVey, blackifh, 
red, green, &c. but it is impure, and generally mixed 
with arfenic and iron. Sometimes it is found in folution 
in the waters of the lakes of Tufcany ; it is found alfo 
in fome of the mountains of Tartary and Thibet, in the 
caverns or grottoes of Puzzoli, &c. But the muriat of 
ammoniac met with in commerce, is the produce of art. 
It is more particularly in Egypt, that this Inline fubftance 
is fabricated from the dung of animals, who feed on fa- 
line plants. They collect the ordure of oxen, camels, 
and feveral other animals; dry it by fpreading it upon 
walls ; then burn, it for the purpofes of fuel. The loot 
which is made by the combultion of thefe matters is put 
into large round glafs bottles, a foot and a half in diame¬ 
ter, terminated by a neck two inches high, which is 
filled to within four inches of the neck; each bottle con¬ 
tains about forty pounds of this foot, and affords nearly 
fix pounds of the fait. Thele veflels are placed on a fur¬ 
nace, fo formed that the neck only is expofed to the air; 
-a fire is made with camel’s dung, and continued for three 
days and three nights; and the fait fublimes on the 
twelfth or thirteenth day. The bottles are then broken, 
and the loaves of fal ammoniac are taken out; thefe loaves, 
which we receive in the form they obtain from the fub- 
liming velfels, are convex and unequal, having a protu¬ 
berance on one fide formed from the neck or the fub- 
liming velfel. The carbonic and footy matters remain at 
the bottom, becaufe they are not volatile; yet there is 
generally a little empyreumatic oil, half-decompofed, 
'which flies up in vapours, and foils the furface of the 
loaves of fal ammoniac. This fait is not formed during 
the combultion of the above-mentioned excrements, but 
feems rather to have pre-exilled in the dung and urine 
of the animals. It is probable that the muriat of foda 
contained in the plants on which thefe animals are fed, 
is decompofed during the procelfes of digellion and afli- 
milation, and changed into muriat of ammoniac; for 
Chaptal obferves, that, when animals live on frefli vege¬ 
tables, their dung affords no muriat of ammoniac; but 
that in winter, on the contrary, when they are fed on 
falted herbs, it affords a great quantity. The muriatic 
acid probably unites with the ammoniac that is conftant- 
ly formed in the animal economy, and the foda remains 
in combination in the animal humours, which always 
contain a quantity of it, particularly in combination 
with phofphoric acid, which feems alfo to be an animal 
produdt. 
There are feveral manufadtories in France where they 
make fal ammoniac, by diftilling all forts of animal fub- 
ftances in a kind of furnaces which perform the office 
of large retorts, and by mixing the aqueous product, 
charged with carbonat of ammoniac, with the mother- 
waters of the brine-pits in the departments of Meurthe, 
Jura, Mont blanc, &c. which contain the muriats of 
lime and of magnefia. Thefe falts are decompofed by 
carbonat of ammoniac by the means of a double attrac¬ 
tion, in which the muriatic acid unites with the volatile 
alkali, and the carbonic acid to the lime and magnefia. 
Thefe two lalt combinations, being infoluble, are preci¬ 
pitated, and the muriat of ammonia remains in the li¬ 
quor : let the liquor be evaporated to drynefs; then fub- 
lime the fait in earthen veffels, which, by opening in the 
middle, facilitate the extraction of the matter, and may 
ferve feveral times. At Franciade, they combine direCtly 
the muriatic acid, drawn from marine fait by fulphuric 
acid, with the produft of animal lubftances diitilled in a 
gun-barrel Baume has eftabiifhed a manufacture of mu¬ 
riat of ammoniac in the neighbourhood of Paris, where 
this frit is entirely compofed by a different procefs from 
that of the Egyptians, who only extracted it. Baumels 
fait is much purer than the Egyptian. 
Sal ammoniac is now made in large quantities in Eng¬ 
land. The volatile alkali is obtained in an impure liquid 
ftate from foot or bones, or any other lubltance that af¬ 
fords it; to this the fulphuric acid is added; and the ful- 
phat of ammoniac thus produced, is decompofed by 
muriat of foda by double affinity; the fulphuric com¬ 
bining with the mineral alkali, and the muriatic acid 
with the volatile alkali. The liquor therefore contains 
fulphat of foda and muriat of ammoniac, which are fe- 
parated by cryflallization; and the muriat of ammoniac 
is fublimed into cakes for fale. The cheapnefs of the 
fulphuric acid, and of common fait, is the caufe why 
they are made ufe of inflead of the muriatic acid, witli 
which the muriat of ammoniac might have been diredly 
formed. Lord Dundonald extracts volatile alkali from 
pit-coal; but whether it can be afforded cheaper for the 
general purpofes of commerce than that of the above pro¬ 
cefs, is not yet afeertained. 
In chemical laboratories, this fait is prepared by a di¬ 
rect combination of muriatic acid with ammoniac to the 
point of faturation. Its talle is pungent, acrid, oily, ar.d 
ammoniacal. It poffeffes a Angular phyfical property, 
namely, a kind of duCtility or eiafticity, fo that it re¬ 
bounds under the hammer, and may be bended j a cir- 
cumftance which renders it difficult to pulverize. Heat 
does not decompofe, but reduces it to vapours. Thrown 
on coals, it fpeedily volatilizes in white fumes ; and, by 
applying an inverted jar, it will be lined with a white 
powder, which is muriat of ammoniac. When the ope¬ 
ration is performed in the large way, a long-necked ma- 
trafs is ufed, and the aperture flopped with paper to pre¬ 
vent lofs. As this fait is very volatile, this method is 
ufed to procure it in a ftate of purity. Linnaeus recom¬ 
mends this fublimation to be performed in circular veflels, 
that is, cut all round, or fliaped like wafhball boxes. 
This fait is not fenfibly changed by expolure to the air. 
The metallic oxyds decompofe it; the manner of operat¬ 
ing we fhall {hew when we come to fpeak of Metals. 
Water, at the temperature of io° diffoives 0-35 of its 
weight; boiling water dillolves much more, fo that a 
great quantity of cryltals are depofited in cooling. Min¬ 
gled with ice, it produces a considerable degree of cold. 
Its cryftals are quadrangular prifms, crowned with four- 
fided pyramids. Some acids, efpecially the fulphuric, 
decompofe this fait; muriatic acid and fulphat of am¬ 
moniac are produced. With nitric acid, it forms a kind 
of aqua regalis, which diffoives gold : the nitric acid de- 
compofes the muriat of ammoniac in the cold, but not 
in the heat. 
Muriat of ammoniac is decompofed by barytes, ftron- 
tian, lime, and even by magnefia, if caloric be employ¬ 
ed : on this property is founded the art of preparing ain.- 
moniac : Take two parts of lime, and one of fal ammo¬ 
niac, both pulverifed; put them into a good ftone retort, 
to which adapt a tube and a tubulated balloon, or a two¬ 
necked bottle, whence goes a tube which communicates 
with a bottle filled witli water; if one is net fuffioient, 
ufe two, three, &c. The quantity of water in the bot¬ 
tle fhould be nearly equal to the fait made ufe of. The 
apparatus, being well luted, is to be heated by degrees; 
as the ammoniac is difengaged in the ftate of gas, it is 
diffolved by the water, and forms what was formerly 
called fluor volatile alkali. The muriatic acid remains in 
the retort united to the lime; this has alfo been called Bald- 
swin's phofpkorus, becaufe by friction in the dark it emits 
fparks of light. Expofed in a moift place, it melts in 
part, becoming a thick liquid fmooth to the touch, which 
occaftoned it to be called oil of lime. Powdered lime tri¬ 
turated with muriat of ammoniac, will alio difengage 
ammoniacal gas. The two fixed alkalis decompofe the 
ammoniacal muriat, in the fame manner as lime ; and 
they in like manner difengage pure ammoniac in the ga- 
feous form. 
This fait is very ufeful in the arts, in chemiftry, and 
in medicine. It is employed in dying, to brighten cer¬ 
tain colours; by brafiers, to cleanfe the furface of cop¬ 
per, previous to its being tinned; in alfaying, to prove 
the 
